Spring REST get list from another class

Question

I am new to both Spring and the REST API overall but I am now trying to make one. So from my controller, I want to return a list of files that another method returns in another class. The code probably says more then I can explain:

   @RequestMapping("/backup")
    public @ResponseBody List<FileInfo> backupFiles() {
        return //Here i want to return the list of files
    }

This is in my restController the "method" i want to return a list of FileInfo and today it already exists a method that does this that looks like this

 private List<String> listBackupFiles() {
    List<FileInfo> files = util.listBackupFilesInLocalDir(localStorage);
    fileNameToSize = files.stream()
                          .collect(toMap(f -> f.name, f -> f.size));
    return files.stream()
                .map(f -> f.name)
                .collect(toList());
}

So basically, I want to when someone goes to /backup I want the above method to trigger and return the list of files to my restController that then returns it to the requester. I don't know if this is even possible or if there is a better way to do this. I take any tips on how to tackle this problem.

I see that, the service listBackupFiles() returns a String, but in your rest controller you are returning List<FileInfo>. This is not right! — Mohith Kumar
– Mohith Kumar, Commented Mar 14, 2018 at 12:31
You need to create an instance of the other class and then call the method. If the listBackupFiles() method is in a separate class from your controller, you could make a new instance of that class in the controller or if you are using spring beans, you can @Autowire the spring managed instance into your controller. — randal4
– randal4, Commented Mar 14, 2018 at 12:31
you need to put the list in json before return, and use @Autowire to access the class — xMilos
– xMilos, Commented Mar 14, 2018 at 12:58

Montassar El Béhi · Accepted Answer · 2018-03-14 13:21:55Z

1

The controller would be:

  // @RestController = @Controller + @ResponseBody
  @RestController
    public class BackupController {  

        @Autowired
        private BackupService backupService;

        // you don't need @ResponseBody as you use @RestController
        @RequestMapping("/backup")
        public List<FileInfo> backupFiles() {
            return backupService.listBackupFiles()
        }
    }

The service interface would be:

public interface BackupService {

     public List<FileInfo> listBackupFiles();
}

The service implementation would be:

@Service
public class BackupServiceImpl implements BackupService {

    public List<FileInfo> listBackupFiles() {
        // localStorage come from
        // maybe Util has it as static method, else inject it
        return util.listBackupFilesInLocalDir(localStorage);
    }
}

Hope was helpful :)

edited Mar 14, 2018 at 13:21

answered Mar 14, 2018 at 13:13

Montassar El Béhi

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1 Comment

novafluff Over a year ago

i get duplicate class error on the "BackupService" class and renaming fixes nothing. feels like this would work but cant get past this

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